From: Glauber Costa <glommer@parallels.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: linux-kernel@vger.kernel.org, paul@paulmenage.org,
lizf@cn.fujitsu.com, ebiederm@xmission.com, davem@davemloft.net,
gthelen@google.com, netdev@vger.kernel.org, linux-mm@kvack.org,
kirill@shutemov.name, avagin@parallels.com, devel@openvz.org,
eric.dumazet@gmail.com, cgroups@vger.kernel.org
Subject: Re: [PATCH v7 00/10] Request for Inclusion: per-cgroup tcp memory pressure
Date: Fri, 2 Dec 2011 16:04:08 -0200 [thread overview]
Message-ID: <4ED91318.1030803@parallels.com> (raw)
In-Reply-To: <20111130111152.6b1c7366.kamezawa.hiroyu@jp.fujitsu.com>
On 11/30/2011 12:11 AM, KAMEZAWA Hiroyuki wrote:
> On Tue, 29 Nov 2011 21:56:51 -0200
> Glauber Costa<glommer@parallels.com> wrote:
>
>> Hi,
>>
>> This patchset implements per-cgroup tcp memory pressure controls. It did not change
>> significantly since last submission: rather, it just merges the comments Kame had.
>> Most of them are style-related and/or Documentation, but there are two real bugs he
>> managed to spot (thanks)
>>
>> Please let me know if there is anything else I should address.
>>
>
> After reading all codes again, I feel some strange. Could you clarify ?
>
> Here.
> ==
> +void sock_update_memcg(struct sock *sk)
> +{
> + /* right now a socket spends its whole life in the same cgroup */
> + if (sk->sk_cgrp) {
> + WARN_ON(1);
> + return;
> + }
> + if (static_branch(&memcg_socket_limit_enabled)) {
> + struct mem_cgroup *memcg;
> +
> + BUG_ON(!sk->sk_prot->proto_cgroup);
> +
> + rcu_read_lock();
> + memcg = mem_cgroup_from_task(current);
> + if (!mem_cgroup_is_root(memcg))
> + sk->sk_cgrp = sk->sk_prot->proto_cgroup(memcg);
> + rcu_read_unlock();
> ==
>
> sk->sk_cgrp is set to a memcg without any reference count.
>
> Then, no check for preventing rmdir() and freeing memcgroup.
>
> Is there some css_get() or mem_cgroup_get() somewhere ?
>
There were a css_get in the first version of this patchset. It was
removed, however, because it was deemed anti-intuitive to prevent rmdir,
since we can't know which sockets are blocking it, or do anything about
it. Or did I misunderstand something ?
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next prev parent reply other threads:[~2011-12-02 18:04 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-29 23:56 Glauber Costa
2011-11-29 23:56 ` [PATCH v7 01/10] Basic kernel memory functionality for the Memory Controller Glauber Costa
2011-11-30 0:48 ` KAMEZAWA Hiroyuki
2011-11-29 23:56 ` [PATCH v7 02/10] foundations of per-cgroup memory pressure controlling Glauber Costa
2011-11-30 0:43 ` KAMEZAWA Hiroyuki
2011-12-02 17:46 ` Glauber Costa
2011-12-05 1:59 ` KAMEZAWA Hiroyuki
2011-12-05 9:06 ` Glauber Costa
2011-11-29 23:56 ` [PATCH v7 03/10] socket: initial cgroup code Glauber Costa
2011-11-30 1:07 ` KAMEZAWA Hiroyuki
2011-11-29 23:56 ` [PATCH v7 04/10] tcp memory pressure controls Glauber Costa
2011-11-30 1:49 ` KAMEZAWA Hiroyuki
2011-12-02 17:57 ` Glauber Costa
2011-12-05 2:01 ` KAMEZAWA Hiroyuki
2011-11-29 23:56 ` [PATCH v7 05/10] per-netns ipv4 sysctl_tcp_mem Glauber Costa
2011-11-29 23:56 ` [PATCH v7 06/10] tcp buffer limitation: per-cgroup limit Glauber Costa
2011-11-30 2:00 ` KAMEZAWA Hiroyuki
2011-11-29 23:56 ` [PATCH v7 07/10] Display current tcp memory allocation in kmem cgroup Glauber Costa
2011-11-29 23:56 ` [PATCH v7 08/10] Display current tcp failcnt " Glauber Costa
2011-11-30 2:01 ` KAMEZAWA Hiroyuki
2011-11-29 23:57 ` [PATCH v7 09/10] Display maximum tcp memory allocation " Glauber Costa
2011-11-30 2:02 ` KAMEZAWA Hiroyuki
2011-11-29 23:57 ` [PATCH v7 10/10] Disable task moving when using kernel memory accounting Glauber Costa
2011-11-30 2:22 ` KAMEZAWA Hiroyuki
2011-12-02 18:11 ` Glauber Costa
2011-12-05 2:18 ` KAMEZAWA Hiroyuki
2011-12-05 9:18 ` Glauber Costa
2011-12-06 0:07 ` KAMEZAWA Hiroyuki
2011-11-30 2:11 ` [PATCH v7 00/10] Request for Inclusion: per-cgroup tcp memory pressure KAMEZAWA Hiroyuki
2011-12-02 18:04 ` Glauber Costa [this message]
2011-12-05 2:06 ` KAMEZAWA Hiroyuki
2011-12-05 9:09 ` Glauber Costa
2011-12-05 9:51 ` KAMEZAWA Hiroyuki
2011-12-05 10:28 ` Glauber Costa
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